Method of manufacturing sensor device

ABSTRACT

A method of manufacturing a sensor device is provided. In the method, sensing electrodes are formed on a substrate, a sensing material layer is formed on the sensing electrodes. The sensing material layer is etched to form a first nanowire sensing region, a second nanowire sensing region and a third nanowire sensing region respectively between every two sensing electrodes of the sensing electrodes. A dielectric layer is formed to cover the first nanowire sensing region, the second nanowire sensing region and the third nanowire sensing region, and the first nanowire sensing region and the third nanowire sensing region are exposed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims the prioritybenefit of U.S. patent application Ser. No. 14/961,906, filed on Dec. 8,2015, now allowed. The prior application Ser. No. 14/961,906 claims thepriority benefit of Taiwan application serial no. 104135766, filed onOct. 30, 2015. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The disclosure relates a method of manufacturing a sensor device thatsenses gas, humidity and temperature.

BACKGROUND

The three important layers in the Internet of Things (IoT) are theperception layer, the internet layer and the application layer, and themost important component in the perception layer is the sensor.Therefore, as the technology IoT continues to develop, the demands forsensors increase correspondingly. Currently, sensors that are miniature,low in power consumption and highly sensitive are the most demanding inapplications, especially for wearable or mobile phone devices.

Presently, the most fundamentally and customarily used sensors are gas,temperature, and humidity sensors, wherein in most gas sensors, atemperature sensor and a humidity sensor are integrated on an extrasystem board for performing calibrations under the different ambientconditions to provide a better accuracy. Alternatively speaking, mostgas sensors are arranged with temperature and humidity sensors. However,for wearable or mobile phone devices, the space for accommodatingsensors is very limited; hence, to miniaturize and integrate sensors ofvarious functions in a same fabrication process has been activelypursued by the relevant industries.

SUMMARY

An exemplary embodiment of the disclosure relates to a method formanufacturing a sensor device. The method includes forming a pluralityof sensing electrodes on a substrate, followed by forming a sensingmaterial layer on the sensing electrodes and then etching the sensingmaterial layer to form a first nanowire sensing region, a secondnanowire sensing region and a third nanowire sensing region respectivelybetween every two sensing electrodes. A dielectric layer is furtherformed to cover the first nanowire sensing region, the second nanowiresensing region and the third nanowire sensing region, and the firstnanowire sensing region and the third nanowire sensing region aresubsequently exposed.

Several exemplary embodiments accompanied with figures are described indetail below to further describe the disclosure in details.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding,and are incorporated in and constitute a part of this specification. Thedrawings illustrate exemplary embodiments and, together with thedescription, serve to explain the principles of the disclosure.

FIG. 1 is a stereoscopic schematic view exemplarily illustrating asensor device according to a first embodiment of the disclosure.

FIG. 2 is a stereoscopic schematic view exemplarily illustrating asensor device according to a second embodiment of the disclosure.

FIG. 3 is a circuit diagram of an exemplary sensor device according to athird embodiment of the disclosure.

FIGS. 4A, 4B-1, 4B-2, 4C, 4D-1, 4D-2 and 4E are schematic viewsexemplarily illustrating respective steps of a method for manufacturinga sensor device according to a fourth embodiment of the disclosure.

FIGS. 5A-1, 5A-2, 5B-1, 5B-2, 5C-1, 5C-2, 5D-1 and 5D-2 are schematicviews exemplarily illustrating variations of the fourth embodiment ofthe disclosure on the method for manufacturing a sensor device.

FIGS. 6A to 6E are schematic views exemplarily illustrating variationsof the fourth embodiment of the disclosure on the method formanufacturing a sensor device.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically shown in order to simplify the drawing.

FIG. 1 is a stereoscopic schematic view exemplarily illustrating asensor device according to a first embodiment of the disclosure.

In the embodiment as shown in FIG. 1, a sensor device includes asubstrate 100, a plurality of sensing electrodes 102 a-102 c, a humiditynanowire sensor 104, a temperature nanowire sensor 106, and a gasnanowire sensor 108. The substrate 100 may be, for example, a siliconchip or other types of appropriate substrate. The sensing electrodes 102a-102 c are formed on the substrate 100 and the size of each sensingelectrode 102 a-102 c is 50 μm×50 μm or more to facilitate sensing. Thematerial of the above sensing electrodes 102 a-102 c may be selectedfrom, for example, at least one pure metal of or an alloy of platinum(Pt), titanium (Ti), tungsten (W), copper (Cu), aluminum (Al), butexcluding pure copper. If the material of the sensing electrodes 102a-102 c is, for example, an alloy, the material of the sensingelectrodes 102 a-102 c may include CuAl, TiCu, TiW, TiCuAl, etc. Thehumidity nanowire sensor 104, the temperature nanowire sensor 106, andthe gas nanowire sensor 108 are also configured on the substrate 100. Inthe embodiment, the humidity nanowire sensor 104 includes an exposedfirst nanowire sensing region 110 and two sensing electrodes 102 a thatare respectively connected with two ends of the first nanowire sensingregion 110. The temperature nanowire sensor 106 includes a secondnanowire sensing region 112, two sensing electrodes 102 b that arerespectively connected with two ends of the second nanowire sensingregion 112 and a dielectric layer 114 covering the second nanowiresensing region 112. The gas nanowire sensor 108 includes an exposedthird nanowire sensing region 116 and two sensing electrodes 102 c thatare respectively connected with two ends of the third nanowire sensingregion 116.

From the perspectives of reducing the manufacturing cost, the abovefirst, second and third nanowire sensing regions 110, 112 and 116 areformed with a same sensing material layer; further, the size of thefirst nanowire sensing region 110 will have different sensitives fordifferent humidity levels, the size of the second nanowire sensingregion 112 will also affect its sensitivity on temperatures, and thedifferent nanowire diameters of the third nanowire sensing region 116will have different sensitivities for different gases. Therefore, thesizes (diameters) of the nanowires of the first, second and thirdnanowire sensing regions 110, 112 and 116 may vary based on the designs,for example, between 100 nm and 1000 nm; in another embodiment, thesizes (diameters) of the nanowires may be between 50 nm and 350 nm.Further, the nanowires of the first, second and third nanowire sensingregions 110, 112 and 116 may have the same or different diameters, butthe disclosure is not limited thereto. The above first, second and thirdnanowire sensing regions 110, 112 and 116 may form with differentsensing material layers. The material used in forming the sensingmaterial layers for the above first, second and third nanowire sensingregions 110, 112 and 116 may include tin oxide (SnO₂), titanium oxide(TiO₂), zinc oxide (ZnO) or polysilicon (poly Si). In some embodiments,a hydrophilic material, such as titanium oxide, tin oxide, etc., isused. The dielectric layer 114 that covers the second nanowire sensingregion 112 may also be covering other parts on the substrate 100 whileexposing the sensing electrodes 102 a-102 c. The material of thedielectric layer 114 may include silicon oxide (SiO₂), silicon nitride(SiN) or other appropriate materials. Although the second nanowireregion 112 is covered by the dielectric layer 114 and a cross-sectionthereof is exposed in the Figures, one can easily realize that thesecond nanowire sensing region 112, which is similar to the firstnanowire sensing region 110 or the third nanowire sensing region 116, isformed with a plurality of nanowires. The first and third nanowiresensing regions 110, 116 in FIG. 1 are exemplified to have threenanowires, whereas the black dots in between signify that the number ofthe nanowires can be increased based on the designs.

FIG. 2 is a stereoscopic schematic view exemplarily illustrating asensor device according to a second embodiment of the disclosure,wherein the same reference numbers are used to represent the same orsimilar structures as shown in FIG. 1.

Referring to FIG. 2, a difference between the first embodiment and thesecond embodiment lies in that the humidity nanowire sensor 200, inaddition to the first nanowire sensing region 110 and the sensingelectrodes 102 a, also includes a hydrophilic material layer 202covering the first nanowire sensing region 110, wherein the hydrophilicmaterial layer may be an ALD layer deposited by the atomic layerdeposition (ALD) technique and a material of the hydrophilic materiallayer 202 may include, but is not limited to, aluminum oxide (Al₂O₃),titanium oxide (TiO₂), tin oxide (SnO₂), Zinc chromate (ZnCr₂O₄) ormagnesium chromate (MgCr₂O₄). Since the first nanowire sensing region110 is covered by the hydrophilic material layer 202, humidityadsorption is increased to thereby enhance the sensitivity of humiditysensing, even when the nanowire of the first nanowire sensing region 110is not formed with a hydrophilic material.

FIG. 3 is a circuit diagram of an exemplary sensor device according to athird embodiment of the disclosure. FIG. 3 illustrates a sensor deviceregion 300 and a reading circuit 310. The sensor device region 300includes a humidity nanowire sensor 302, a temperature nanowire sensor304 and a gas nanowire sensor 306, and the characteristics of thesenanowire sensors can be referred to the first and second embodiments andwill not reiterated herein. The reading circuit 310 in the thirdexemplary embodiment may concurrently read the humidity nanowire sensor302, the temperature nanowire sensor 304 and the gas nanowire sensor 306and convert the readouts from these sensors 302, 304, 306 to digitalsignal outputs. Moreover, the sensor device region 300 may also includea plurality of calibration sensors 308 a-308 c for calibrating theambient conditions. The plurality of calibration sensors 308 a-308 cwhich is connected respectively with the humidity nanowire sensor 302,the temperature nanowire sensor 304 and the gas nanowire sensor 306 atone ends and is grounded at the other ends. The embodiment isexemplified by a half-bridge structure, wherein the lower half-bridgereference resistances of the humidity nanowire sensor 302 and the gasnanowire sensor 306 may directly use the resistances measured by anair-insulated temperature (nanowire) sensor, and the absolutetemperature coefficient of the temperature nanowire sensor 304 isdifferent from that of the lower half-bridge reference resistance toobtain the changes in temperature. The lower half-bridge referenceresistance for the temperature nanowire sensor 304 is not attached bytemperature. The voltage of the midpoint of the half-bridge is an analogvoltage signal, and is converted as N bit digital data after beingprocessed by an ADC (analog-to-digital converter) in the reading circuit310 to facilitate the data comparison by, for example, a MCU(microcontroller) process unit.

Accordingly, when the sensors in the third exemplary embodiment start todetect, the program in the process unit of the reading circuit 310determines which signal to select, and then switches MUX 3 to 1(multiplexer) to obtain the midpoint voltage value of the humidity,temperature and gas nanowire sensors 302, 304 and 306 half-bridgestructures. These values are respectively the responses of the humidity,temperature and gas nanowire sensors 302, 304 and 306 to the changes ofhumidity, temperature and gas. Then, the ADC in the reading circuit 310converts respectively the three analog voltage values to digital values,and sends the ADC converted data to the process unit. The process unitfirst calculates a temperature value from the readout value of thetemperature nanowire sensor 304, and then a calibration value ofhumidity under this temperature is extracted from the calibrationdatabase 320, for example, by implementing a look-up-table approach.After a calibrated humidity value is calculated by the process unit, acalibration value of the gas nanowire sensor 306 under the abovetemperature and humidity is read from the calibration database 320. Theprocess unit again calculates a gas response value under the abovetemperature and humidity. The disclosure is not limited thereto. Thereadout circuit 310 may not use the MUX for the switching; instead,three different ADCs are correspondingly used for the conversion of thehumidity, temperature and gas nanowire sensors 302, 304 and 306.Thereafter, data processing is performed by the process unit.

FIGS. 4A to 4E are schematic views exemplarily illustrating respectivesteps of a method for manufacturing a sensor device according to afourth embodiment of the disclosure, wherein FIGS. 4A, 4B-1, 4C and 4D-1are cross-sectional view, while FIGS. 4B-2, 4D-2, and 4E are perspectiveviews.

Referring to FIG. 4A, the substrate 400 includes an interconnectionlayer 402 thereon, and this interconnect layer 402 includes plurallayers of metal conductive layers and dielectric layers (not shown),which may be connected with a transistor type of devices (not shown)disposed on the substrate 400, wherein the interconnection layer 402 isexemplified by a topmost metal layer 404 in FIG. 4A. Moreover, theinsulation layer 406 formed on the interconnection layer 402 includes aplurality of contacts 408. Thereafter, a conductive layer 410 is formed,but the disclosure is not limited thereto. The interconnection layer 402and the contacts 408 thereon in FIG. 4A may be omitted, and theconductive layer 410 is formed directly on the substrate 400.

Referring to FIGS. 4B-1 and 4B-2, the conductive layer 410 of FIG. 4A isetched to from a plurality of sensing electrodes 412, and the materialof the sensing electrodes 412 may be selected from at least a pure metalof or an alloy of platinum (Pt), titanium (Ti), tungsten (W), copper(Cu) and aluminum (Al), but excluding pure copper. If an alloy is used,the sensing electrodes 412 may be formed with CuAl, TiCu, TiW, TiCuAl,etc. Afterwards, an insulation layer 414 is deposited to cover thesensing electrodes 412 and fill the gaps between the sensing electrodes412, wherein the insulation layer 414 is, for example, an oxide layer.Thereafter, a CMP (chemical mechanical polishing) process, for example,is performed to expose the sensing electrodes 412 for facilitating thesubsequent nanowire process and connection.

Continuing to FIG. 4C, a sensing material layer 416 is formed on thesensing electrodes 412. The material of the sensing material layer 416is, for example, tin oxide (SnO₂), titanium oxide (TiO₂), Zinc oxide(ZnO) or polysilicon (Poly Si). The method used in forming the sensingmaterial layer 416 includes, but is not limited to, PVD sputtering,furnace deposition, chemical bath deposition, etc.

Referring to FIGS. 4D-1 and 4D-2, the sensing material layer 416 isetched to form a first nanowire sensing region 418, a second nanowiresensing region 420 and a third nanowire sensing region 422 respectivelybetween every two sensing electrodes 412. The dimensions (diameters) ofthe above first, second and third nanowire sensing regions 418, 420, 422may vary according to the design requirements, for example, ranging from10 nm to 1000 nm, and in some embodiments, they may range from 50 nm to350 nm. Further, the first, second and third nanowire sensing regions418, 420, 422 may have the same or different diameters.

Referring to FIG. 4E, a dielectric layer 424 is formed to cover thefirst, second and third nanowire sensing regions 418, 420, 422. Thedielectric layer 424 may be formed with, for example, silicon oxide(SiO₂) or silicon nitride (SiN). Thereafter, the dielectric layer 424 onthe first and third nanowire sensing regions 418, 422 is removed toexpose the first and third nanowire sensing regions 418, 422, whichrespectively serve as the humidity nanowire sensor and the gas nanowiresensor. The second nanowire sensing region 420 serving as thetemperature nanowire sensor, however, is covered by the dielectric layer424. The first nanowire sensing region 418 serving as the humiditynanowire sensor is exposed directly to air; hence, the material used informing thereof is a hydrophilic material, such as titanium oxide, tinoxide, etc. Further, in the present embodiment, when the dielectriclayer 424 on the first and third nanowire sensing regions 418 and 422 isremoved, the dielectric layer on the sensing electrodes 412 may also beremoved concurrently to form a plurality of pad openings 426.

FIGS. 5A-1 to 5D-2 are schematic views exemplarily illustratingvariations of the fourth embodiment of the disclosure on the method formanufacturing a sensor device, wherein FIGS. 5A-1, 5B-1, 5C-1 and 5D-1are cross-sectional views and FIGS. 5A-2, 5B-2, 5C-2 and 5D-2 areperspective views.

Referring to FIGS. 5A-1 and 5A-2, after the first, second and thirdnanowire sensing regions 418, 420, 422 are formed, continuing from FIGS.4D-1 and 4D-2, a dielectric layer 500 is formed to cover the first,second and third nanowire sensing regions 418, 420, 422, followed byexposing the first nanowire sensing region 418 and the third sensingregion 422. The above dielectric layer 500 may include silicon oxide(SiO₂) or silicon nitride (SiN), for example.

Thereafter, referring to FIGS. 5B-1 and 5B-2, a hydrophilic materiallayer 502 is coated on the substrate 400, wherein the hydrophilicmaterial layer 502 may include, for example, aluminum oxide (Al₂O₃),titanium oxide (TiO₂), tin oxide (SnO₂), Zinc chromate (ZnCr₂O₄) ormagnesium chromate (MgCr₂O₄). A photoresist 504 is further used todefine the location where the hydrophilic material layer is to beretained and to facilitate the removable of the unwanted hydrophilicmaterial. In these two Figures, the photoresist 504 is positioned abovethe first nanowire sensing region 418 and corresponds to the number ofnanowires of the first nanowire sensing region 418, but the disclosureis not limited thereto. The position, the size and the number of thephotoresist 504 may vary according to the design requirements.

Then, continuing to FIGS. 5C-1 and 5C-2, using the photoresist 504 ofFIGS. 5B-1 and 5B-2 as a shield, the exposed hydrophilic material layer502 is removed. The hydrophilic material layer 502 a is formed on thefirst nanowire sensing region 418, while the third nanowire sensingregion 422, which serves as a gas nanowire sensor, is exposed.Ultimately, the photoresist 504 is removed.

Now referring to FIGS. 5D-1 and 5D-2, the dielectric layer 500 on thesensing electrodes 412 is removed to form a plurality of pad openings506. The exposed sensing electrodes 412 may serve as bonding pads orprobe pads.

FIGS. 6A to 6E are schematic views exemplarily illustrating variationsof the fourth embodiment of the disclosure on the method formanufacturing a sensor device.

Referring to FIG. 6A, after forming the first, second and third nanowiresensing regions 418, 420, 422, continuing from FIGS. 4D-1 and 4D-2, adielectric layer 600 is formed to cover the first, second and thirdnanowire sensing regions 418, 420, 422, followed by exposing the firstnanowire sensing region 418. The above dielectric layer 600 may beformed with silicon oxide or silicon nitride, for example.

Now referring to FIG. 6B, a hydrophilic material layer 502 is coated onthe substrate 400, and a photoresist 504 is used to define the locationwhere the hydrophilic material layer is to be retained. The material ofthe photoresist 504 and the hydrophilic material layer 502 are similarto those described above.

Referring to FIG. 6C, using the photoresist 504 of FIG. 6B as a mask,the exposed hydrophilic material layer 502 is removed and a hydrophilicmaterial layer 502 a is formed on the first nanowire sensing region 418.Since the third nanowire sensing region 422 which serves as a gasnanowire sensor has been covered by the dielectric layer 600, it willnot be affected by the fabrication process of the hydrophilic materiallayer 502 a. Further, no hydrophilic material residues will be remainedon any part of the third nanowire sensing region 422. Ultimately, thephotoresist 504 is removed.

Thereafter, referring to FIG. 6D, the dielectric layer 600 on thesensing electrodes 412 is removed to form a plurality of pad openings506.

Continuing to FIG. 6E, the dielectric layer 600 on the third nanowiresensing region 422 is removed to expose the third nanowire sensingregion 422 to serve as a gas nanowire sensor.

In view of the foregoing embodiments of the disclosure, the gas,temperature and humidity nanowire sensors may be concurrently fabricatedto have the three sensors integrated on a same substrate. Accordingly,not only the characteristics of the nanowire sensor, such as highsensitivity, miniature, lower power consumption, etc., are provided, theoverall volume can be greatly reduced to be applied to wearable devicesof IoT. If a reading circuit with sufficient input range is furtherprovided, it may read the sensors as described in the embodiments of thedisclosure and then convert them into digital outputs.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A method for manufacturing a sensor device,comprising: forming a plurality of sensing electrodes on a substrate;forming a sensing material layer on the plurality of sensing electrodes;etching the sensing material layer to form a first nanowire sensingregion, a second nanowire sensing region and a third nanowire sensingregion respectively between every two sensing electrodes of theplurality of sensing electrodes; forming a dielectric layer to cover thefirst nanowire sensing region, the second nanowire sensing region andthe third nanowire sensing region; and exposing the first nanowiresensing region and the third nanowire sensing region.
 2. The methodaccording to claim 1, wherein the step of exposing the first nanowiresensing region and the third nanowire sensing region comprises removingthe dielectric layer on the first nanowire sensing region and the thirdnanowire sensing region to form a plurality of pad openings.
 3. Themethod according to claim 1, further comprising forming a hydrophilicmaterial layer on the first nanowire sensing region after the step ofexposing the first nanowire sensing region and the third nanowiresensing region.
 4. The method according to claim 3, wherein thehydrophilic material layer comprises aluminum oxide (Al₂O₃), titaniumoxide (TiO₂), tin oxide (SnO₂), Zinc chromate (ZnCr₂O₄) or magnesiumchromate (MgCr₂O₄).
 5. The method according to claim 3, furthercomprising removing the dielectric layer on the plurality of sensingelectrodes to form a plurality of pad openings after the step of formingthe hydrophilic material layer.
 6. The method according to claim 1,wherein the step of exposing the first nanowire sensing region and thethird nanowire sensing region comprises: removing the dielectric layeron the first nanowire sensing region; forming a hydrophilic materiallayer on the first nanowire sensing region; and removing the dielectriclayer on the plurality of sensing electrodes to form a plurality of padopenings after forming the hydrophilic material layer; and removing thedielectric layer on the third nanowire sensing region.
 7. The methodaccording to claim 6, wherein the hydrophilic material layer comprisesaluminum oxide (Al₂O₃), titanium oxide (TiO₂), tin oxide (SnO₂), Zincchromate (ZnCr₂O₄) or magnesium chromate (MgCr₂O₄).
 8. The methodaccording to claim 1, wherein the dielectric layer comprises siliconoxide (SiO₂) or silicon nitride (SiN).
 9. The method according to claim1, wherein a material of the plurality of sensing electrodes comprisesat least one pure metal of or an alloy of platinum (Pt), titanium (Ti),tungsten (W), copper (Cu) and aluminum (Al), but excluding pure copper.10. The method according to claim 1, wherein the sensing material layercomprises tin oxide (SnO₂), titanium oxide (TiO₂), zinc oxide (ZnO) orpolysilicon (poly Si).